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Introduction to Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
The concentration of a solution is expressed as the number of grams of solute per liter of solution or number of moles per liter (molar concentration). The concentration of a gas in a mixture of gases is expressed as the percentage (parts per hundred) of the gas in the mixture. It is also expressed in parts per million (1/106; ppm) or parts per billion (1/109; ppb).
Introduction: Background Material
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
In biological systems, it is usually convenient to define chemical potentialκ′˜ for a given substance as chemical potential energy per gram-molecular weight, or mole, of the given substance rather than per particle, where a mole, whose symbol is mol, is formally defined as the amount of substance that contains as many atomic particles, such as molecules, atoms or ions, as 12 g of carbon 12. This number is in fact Avogadro’s constant NA (nearly 6.022 × 1023). One mole of a substance is also the amount in grams that is equal to the molecular weight. The molar concentration, or molarity, of a solute is the number of moles/liter, and is denoted by M. Thus, a concentration of 100 mM of Na+ is equivalent to a 0.1 of a mole of Na+ per liter of solution. It is also 0.1 of a millimole per cm3 of solution.
Chemically Reacting Flows
Published in Greg F. Naterer, Advanced Heat Transfer, 2018
Assuming the stoichiometric amount of reactants are converted to products, without excess reactants or by-products as a result of an incomplete reaction, then the reaction rate (r) in a closed system of constant volume can be expressed as: r=−1adCAdt=−1bdCBdt=1ddCDdt=1edCEdt where Ci refers to the molar concentration of species i. The molar concentration represents the amount of a constituent in moles divided by the volume of the mixture. The units of the reaction rate are typically mol/Ls. The reaction rate is always positive. A negative sign above is used when a reactant is consumed and hence its concentration is decreasing. It can be observed that the rate of reaction is inversely proportional or normalized by the stoichiometric number so that it becomes independent of which reactant or product species is used in the analysis.
Enhancing the anticorrosion performance of mild steel in sulfuric acid using synthetic non-ionic surfactants: practical and theoretical studies
Published in Green Chemistry Letters and Reviews, 2021
Metwally Abdallah, Nizar El Guesmi, Arej S. Al-Gorair, Refat El-Sayed, Aseel Meshabi, Mohamed Sobhi
The free energy of adsorption (ΔG°ads) was computed from the subsequent relation (44): where the value (55.5) is the molar concentration of water in solution. Generally if the values of ΔG°ads around −20 kJ/mol or lower. The process can be referred to as the physical adsorption; while those around −40 kJ/molor higher elucidate chemical adsorption. The obtained values of ΔG°ads are equal to −34.39, −36.58, and −38.36 kJ/mol which demonstrates that the adsorption of NI Surf. on MS surfaces is a mix of physical and chemical adsorption. The high values of ΔG°ads and their negative values indicate that the adsorption reaction of NI Surf. onto the surface of MS is spontaneously and accompanied with a vigor efficient adsorption of such compounds.
Selective oxidation of glycerol to mesoxalic acid by laccase/2,2,6,6-tetramethylpiperidine-N-oxyl system: Effect of process conditions and the kinetic modeling
Published in Chemical Engineering Communications, 2019
Chi Shein Hong, Sim Yee Chin, Chin Kui Cheng, Gek Kee Chua
Glycerol oxidation products were determined by using a HPLC (Agilent 1260 Infinity Liquid Chromatography, United States) equipped with Diode Array Detector (DAD) and Refractive Index Detector (RID). Deionized water containing 3 mM H2SO4 was used as mobile phase with a flow rate of 0.5 mL/min. A 300 mm Phenomenex Rezek ROA column (300 mm × 7.8 mm) was employed for the separation and sample injection volume was set at 10 µL. Column and RID temperature were maintained at 75 and 35 °C, respectively. DAD wavelength was fixed at 210 nm. Data acquisition was performed by Agilent Chemstation Rev C01.04(35) software. The components were identified from the chromatograms of the samples by comparing their retention times with the respective standard components. The mole percentage of Gly converted was calculated based on the comparison of initial molar concentration of Gly and final molar concentration of Gly detected at time t.
Assessment of combustion models for numerical simulations of a turbulent non-premixed natural gas flame inside a cylindrical chamber
Published in Combustion Science and Technology, 2018
Cristiano Vitorino da Silva, Diego Luís Deon, Felipe Roman Centeno, Francis Henrique Ramos França, Fernando Marcelo Pereira
where is the temperature exponent in each chemical reaction , is the activation energy and is the pre-exponential coefficient. is the molar concentration of the kth reacting chemical species, is the concentration exponent in each reaction and and are, respectively, the molecular mass and the stoichiometric coefficient of kth chemical species in the cth chemical reaction. Parameters of Eq. (21) for the two-step mechanism under consideration, Eqs. (1) and (2), are presented in Table 1. Eq. (21) is employed when the reactions are limited by the chemical kinetics.